Fine adjustment mechanism for stock feeding device

ABSTRACT

A device for effecting small adjustments in the stroke of a stock feeding mechanism while the latter is operating. The element which controls the stroke does not move during the stock feeding operation and therefore may readily be adjusted by the operator to vary the length of feed as required. The device is applicable to a reciprocable type of feeding mechanism in which the angular relation between an oscillating connecting rod and a rectilinearly movable member linked thereto may be adjusted so as to alter the excursions of the latter member and of the stock engaging elements connected thereto.

United States Patent [1 1 Granger [451 Jan. 9, 1973 s41 FINE ADJUSTMENT MECHANISM FOR 3,282,218 11/1966 Bauer ..74/600 STOCK IN EVI 2,164,806 7/1939 Eickman ..s3/244 3,099,180 7/1963 Munschauer, Jr. et a1... ..83/244 1 lnvemofl Richard Granger, Sutton Cold- 3,122,042 2/1964 Littell et a1. ......s3/244 field, ngland 3,528,318 9/1970 Huston etal. ..74 600 Assign: Cincinnati Mnacron Inc. Cincim 3,529,542 9/1970 Rasenberger ..l00/2l5 Ohio FOREIGN PATENTS OR APPLICATIONS Filedr g- 20, 1970 668,397 8/1963 Canada ..s3/244 21 Appl. No.: 65,463

Primary Examiner-Milton Kaufman 0 Assistant Examiner-Wesley S. Ratliff, Jr. Foreign Application Priority Data Attorney-Howard T. Keiser and Jack .1. Earl A 21,1969 G H! 'ta' ..41,762 69 n m I I 57 ABSTRACT A device for effecting small adjustments in the stroke 83/ of a stock feeding mechanism while the latter is [51] Int. Cl ..Fl6h 29/20 o rating Th lement which controls the stroke does Fleld of Search 46, not move during the stock feeding operation and 100/215 therefore may readily be adjusted by the operator to vary the length of feed as required. The device is ap- [56] References Cited plicable to a reciprocable type of feeding mechanism in which the angular relation between an oscillating UNITED STATES PATENTS connecting rod and a rectilinearly movable member 2,395,789 2/1946 0 kle linked thereto may be adjusted so as to alter the ex- 2,461,688 2/1949 lllsche cursions of the latter member and of the stock engag- 3,078,734 2/1963 Wiig ing elements connected thereto. 3,090,250 5/1963 Budlong 3,244,023 5/1966 Baringer et al ..74/600 4 Claims, 5 Drawing Figures I 25 I 1' l 47 l 1,,

'11! a llzi a- 4 E l 9 E 1 4s l L o n 37 28g l o 'l 44 52 PATENTEDJAN 9mm 3.709 050 sum 3 OF 3 BACKGROUND OF THE INVENTION This invention relates to stock feeding devices for advancing stock along a feed path in a series of steps. Each feeding device comprises a body or supporting structure, an output member movably mounted thereon for engaging the stock to impart the required steps thereto, and a rotary input member mounted thereon and operatively connected with the output member.

The invention has been developed primarily to meet the requirements of a stock feeding device of the kind specified for advancing stock in the form of strip or sheet material through the working station of a machine tool which includes at least one tool carrying member disposed at the working station and movable in a direction to bring the tool, when carried thereby, into and out of engagement with the stock.

In many instances it is important that the magnitude of each individual feed step should be accurately maintained. For example, where the stock is strip or sheet material and the machine tool is a power press, the tools of the power press at the working station operate on longitudinally spaced areas of the strip, and for maximum economy, these are required to be placed as closed as possible to each other consistent with the deformation of the metal in one are not adversely affecting the metal in the adjoining areas. If the feed step lengthens, the amount of stock wasted may be significant over a long period of working, while if it shortens, malformed products can result. The requirement for accuracy asto the magnitude of the feed step may be even greater where a series of tools are provided at respective working stations, and the second or subsequent tools are of such form as to carry out subsequent operations on respective areas of the stock which have already undergone an earlier operation.

In general, the rotary input member of a stock feeding device of the kind specified is required to be driven in coordination with a member of the machine tool moving in predetermined timed relation with the tool or tools. In the case of a power press, for example, there is provided a driving shaft having a crank thereon for moving the tool carrying member to and from the work. The driving shaft also carries a further crank or eccentric for driving the input member of stock feeding device by way of a reciprocating member.

DESCRIPTION OF THE PRIOR ART There are two general arrangements which are commonly in use for connecting the eccentric with the input member of the stock feeding device. In the first of these a variable throw crank on the driving shaft is coupled to the rotary input member of the stock feeding device through a connecting rod and a lever extending radially with respect to the axis of rotation of the rotary input member so that the latter is oscillated forwardly and reversely.

In the second general arrangement, a variable throw crank or eccentric, as described in the preceding paragraph, is coupled to one end of a rack and the rack meshes with a pinion which drives the rotary input member of the stock feeding device, so that again the input member of the stock feeding device is oscillated forwardly and reversely.

Initial adjustment of the magnitude of the feed step provided by the output member of the stock feeding device is normally accomplished by adjusting the throw of the eccentric or crank on the driving shaft of the machine tool. However, the operating parameters of the machine tool, for example the speed of operation thereof, the condition of the stock, the temperature conditions, and other systematically or randomly variable parameters, do, in practice, bring about variations 0 of the magnitude of the feed step imparted to the stock from the nominal or pre-set value. There is accordingly a requirement to enable a corrective adjustment, usually termed a fine adjustment, to be made whichwill restore the magnitude of of the feed step to its nominal or pre-set value. Such adjustment cannot readily be effected by adjusting the variable throw crank or eccentric on the driving shaft of the machine tool since this is continuously in motion while the machine tool is in operation.

Corrective or fine adjustment means have been developed where the coupling between the driving shaft of the machine tool and the input member of the stock feeding device is of the first general kind above referred to. Such corrective or fine adjustment means can be operated while the machine tool and associated stock feed device is in operation. It consists essentially of an arrangement whereby the effective length of the crank or lever arm extending radially from the axis of rotation of the rotary input member of the stock feeding device can be adjusted, notwithstanding that the latter is subjected continually to oscillatory motion forwardly and reversely.

Corrective or fine adjustment means for arrangements wherein coupling between the driving shaft and the rotary input member of the stock feeding device is by way of rack and pinion elements are less satisfactory. Certain of them involve the use of a flexible sha'ft rotatable by ahand wheel stationarily mounted in relation to the stock feeding device. This shaft is connected to the movable adjustment device such as the variable throw crank ordinarily provided on the driving shaft of the machine tool. In another proposed arrangement, the rack element is connected to a variable throw crank on the driving shaft of the machine through the intermediary of a lever having a fulcrum on the frame of the machine pivoted to both the rack element and to a link connected pivotally to the crank. In this arrangement, mechanism is provided to adjust the position of the fulcrum of the lever and hence the velocity ratio afforded thereby. This mechanism involves a rotary shaft incorporating universal joints in order to accommodate the motion of the lever.

An objection to the first of these arrangements is that, due to the continual motion to which the flexible shaft is subjected, it has a limited service life. Furthermore there is difficulty in locking the arrangement in an adjusted position and hence in maintaining the magnitude of the feed step. In the second arrangement, the structure providing the adjustable fulcrum is complex and this, together with the universal joints which are subjected to continual angular deflection during working of the machine, entails manufacture and assembly of a large -number of components materially increasing the cost of the feeding device.

Nevertheless there are certain advantages in utilizing a rack and pinion coupling means between the driving shaft of the machine tool and the rotary input member of the associated stock feeding device. ln;particular, the magnitude of the feed step which can be imparted conveniently when utilizing this form of coupling means is increased without the necessity of providing gearing for. the purpose of providing a step-up ratio. Also, it eliminates the necessity of increasing the diameter of the output member of the stock feeding device merely to ensure availability of the maximum value of feed step required.

SUMMARY OF THE INVENTION The general object of the present invention is to provide, in association with a stock feeding device, a correc'tive or fine; adjustment means which is simple, and hence inexpensive, to manufacture and is reliable in operation, and is capable of being operated while the machine tool and the stock feeding device are in operation.

According to one aspect of the invention, there is provided, in association with a stock feeding device of the kind specified, a means for coupling the rotary input member of the device to a driving element adapted to provide reciprocatory output motion, said coupling means comprising: an oscillatory element connected to the rotary input member; a reciprocatory element in operative engagement with the oscillatory element to drive same; link means connected between the reciprocatory element and a driving element of the machine; means for determining the geometry of the reciprocatory element and the link means (and thereby the velocity ratio afforded between the driving element and the input member) and mounted on the supporting structure of the machine in a position which is fixed during operation of the device but which can be changed while, the device is in operation to alter said geometry and hence the amplitude of oscillation of the input member.

Reciprocatory movement is intended to include both rectilinear reciprocation and motion composed of a combination'of rectilinear reciprocation and angular motion.

According to a further aspect of the invention there is provided in association with a stock feeding device for a power operated machine, a means for coupling the rotary input member of the stock feeding device to a crank or eccentric on the drive shaft of the machine, said coupling meanscomprising a pinion connected to the rotary input member of the stock feeding device, a rack meshing with the pinion, a guide means mounted in a position which is fixed during operation of the device, said guide means defining a path of reciprocadifferent amplitudes of reciprocation of the rack and,-

hence, different amplitudes of oscillation of the input member of the stock feeding device.

' ln apreferred arrangement, the guide means is mounted forangular adjustment about the axis of oscilstock feeding device in this case being driven from the oscillatory or pinion element meshing with the rack as aforesaid. However, the invention may be applied advantageously in a casewhere stock feeding devices of the kind specified are provided both at the infeed side and at the exit-side of a working station at spaced apart positions along the feed path, the input members of such stock feeding devices being coupled to each other to ensure that they operate in coordination.

In this latter case it sometimes happens that the operations performed upon the stock produce conditions in which there is longitudinal stretch of the stock between the stock feeding devices situated at the infeed and exit sides of the working station. For example, the stock may elongate due to the action of a punch. Also,

if a substantial aperture area is formed in the stock leaving only relatively thin or slender connecting portions, the longitudinal dimension of the stock may stretch under the pulling action exerted by the stock feeding device at the exit side of the working station.

In such circumstances, or where analogousconditions arise, the application to the output member of the stock feeding device at the exit side of a working station, of an amplitude of movement which is exactly equal to that applied to the output member of the stock feeding device at the input side of the station may lead to buckling of the stock at the working station. Alternatively, the stock may fracture and cause obstruction or malfunctioning of the machine tool or the stock feeding device.

Consequently, it is sometimes desirable that a corrective or fine adjustment means be provided in the coupling'means between the input members of the two stock feeding devices. The present invention may be so applied. In this case the stock feeding device situated at one side of the working station would advantageously include rack and pinion elements and a guide means as aforesaid, together with link means coupling the rack element to a driving element driven from or with the input member of the stock feeding device at the other side of the working station, adjustment means being provided for positionally adjusting the guide means associated with the stock feeding device at said one'side of the working station.

it will be understood that the term stock is used generically to include any material required to be advanced along a feed path, and in particular includes strip, sheet, rod or other elongated forms of material as well as particulate or divided material which may require support on a conveyingmember, constituting in this case the output member of the stock feeding device. The term may also include a series of discrete members which collectively form the stock and which would be supported on such conveyor member.

The invention will now be described, by way of example with reference to the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a view in front elevation of one embodiment of the invention applied to a power press on which stock feeding devices are provided at both the infeed and exit sides of a working station;

FIG. 2 is a view in side elevation of the same embodiment and in partial cross section;

FIG. 3 is a fragmentary view on an enlarged scale in side elevation of the one-way clutch device, the input element of which constitutes the input member of the stock'feeding devices at both the infeed and exit sides of the working station;

FIG. 4 is a fragmentary view in cross section taken on the line 44 of FIG. 2 showing part of the adjustment means for fine adjustment of the feed stroke; and

FIG. 5 is a diagrammatic view illustrating an embodiment of the invention as applied for coupling stock feeding devices at opposite sides of the working station of a power press or other machine.

DESCRIPTION OF A PREFERRED EMBODIMENT As illustrated in FIGS. 1 to 4 the invention will be described, by way of example, with reference to the application of stock feeding devices to a power press. Such power press may comprise a frame which includes a bed 11 for supporting the lower of a pair of complementary dies or press tools (not shown). The frame also includes an upwardly extending slideway 12 for supporting a reciprocating ram 13 which forms the tool carrying member for the upper die or press tool. Reciprocating movement is imparted to the ram 13 from a driving shaft 14 carrying a flywheel l5 and having a crank 16 connected by a connecting rod 17 to the ram 13 and journalled in bearings 18 above the slideway. At one end the driving shaft carries a variable throw crank or eccentric 19 forming the driving element for the feeding devices and which provides a reciprocating output motion for this purpose.

The variable throw crank includes a pin 20 which is adjustable radially towards and away from the axis 21 of the driving shaft by any suitable adjustment mechanism which may be of conventional construction, for example a screw 22 which serves to move a nut-block 24 integral with the pin 20 along a radially extending guideway 25 formed in a disc 26 of the crank.

The press may be required to operate upon stock in the form of metal strip and which, for this purpose, is required to be advanced in a series of feed steps over the upper surface of the tool mounted on the bed or table II, from one side towards the opposite side as viewed from the front of the press. For this purpose there is provided at each side of the press, two substantially identical stock feeding devices 27a, 27b. Only one of these will be described, with the component parts thereof being designated by a numeral and a suffix a. Corresponding parts of the other device are designated by like reference numerals with a suffix b.

The feeding devices 27a, 27b may be free standing on the floor or surface on which the press is supported or, as shown herein, they may be secured to the bed 11 at opposite sides thereof.

Referring to the device 27a, this comprises a body or supporting structure 28a in which is mounted upper and lower rolls 29a, 30a carried by spindles 31a, 32a

journalled for rotation about vertically spaced horizontal axes extending transversely of the feed path defined between the rolls and indicated diagrammatically at 33. At least one of these rolls, e.g. 30a, is driven and constitutes the output member of the stock feeding device. The upper roll is vertically movable and urged downwardly by a spring 43a acting on the bearings for spindle 31a which are carried in vertical guides in the body 28a.

The driven roll 30a is rotated intermittently in a forward direction as indicated by arrow 34a in a direction to effect advancement of the stock along the feed path, and a variety of arrangements may be adopted to enable the stock to remain stationary when a portion of the stock is operated upon by the dies or press tools at the working station defined between the latter.

Thus, the two rolls may be brought to rest at the end of each period of rotation in a forward direction whilst remaining in engagement with the stock. Alternatively the two rolls may be subjected to relative movement in a direction to cause separation between their peripheries so that they no longer grip the stock at the end of each feed step, and in this case one or both of the rolls may undergo rotation in a reverse direction.

In the arrangement illustrated, the drive to the roll 30a is derived from a rotary input element 35 constituted by the cylindrical housing of a one-way driving clutch device. The output element 36 of the clutch is keyed or otherwise fixed to a cross shaft 37 journalled in bearings 38a, 38b of the devices 27a, 27b. Driving torque between elements 35 and 36 is established unidirectionally by spring loaded rollers 39 (FIG. 3) 93 in pockets 40. The shaft 37 carries spiral gears 41a, 41b

meshingwith spiral gears 42a, 42b on spindles 32a, 32b

to drive the rolls 30a, 30b. In certain cases it may be possible for the driving roll to be mounted directly on a shaft which constitutes the input member without the intervention of any gearing, pawl and ratchet, or other one-way driving device. A brake device 23, which may be frictional, is provided for preventing overrun of the cross shaft 37.

I For transmitting the requisite intermittent forward rotational movement to'the driven roll the input element 35 has fixed to it or, as illustrated, is formed integrally with, a pinion 44 itself subjected to rotation in a forward direction and in a reverse direction, and this motion is derived from the variable throw crank 19.

The pinion 44 constitutes one element of a coupling means which further comprises a rack 45 meshing with the pinion 44, and a link means 46 which conveniently is in the form of a single link bar 47 pivotally connected at one end to the pin 20 of the crank 19, and having a pivot pin 48 at the other end connecting it to the rack. A longitudinally extending axis 54 drawn through the axes of rotation defined by the pivot pins 20 and 48 constitutes the reference axis of the link means.

The coupling means further comprises a guide means for determining the geometry of the link means and rack. Such guide means may conveniently comprise a housing 49 which is pivotally connected to the body 28a of an associated one 27a of the stock feeding devices situated at the infeed side of the bed or table.

The housing 49 includes a part-cylindrical portion 50 for enclosing the pinion 44, and an elongated, generally tubular, portion 51 of square or rectangular cross section extending generally tangentially to the .part-cylindrical portion 50, and formed integrally with a guideway 52 for constraining the rack 45 to endwise movement. The guideway also maintains the rack in meshing relation with the pinion 44, and determines the angular relation between the path indicated by the line 53 for the rack and the reference axis 54 of the link means.

The housing 49 is mounted by means of a boss 55 on the shaft 37 so as to be capable of positional adjustment angularly about the shaft 37 but is held stationary as hereinafter described during operation of the pressand feed devices. It will be evident that rotation of the variable throw crank or eccentric 19 produces motion of the link bar 47 which is composed of rectilinear endwise components of movement at the lower end of link bar 47 parallel to the reference axis 53' and circular components of movement at its upper end.

When the reference axis 53 passes through the axis 21 of rotation of the crank 19, the amplitude of reciprocating movement which is imparted to the rack 45. is equal to twice the throw of the crank. If, however, the housing 49 is positionally adjusted angularly about the axis of shaft 37 so that the reference axis 53 does not pass through the axis 21, the amplitude of reciprocation of the rack 45 is increased. This is so because the intercept, cut off by reference circles centered on axis 53 and drawn through the crank pin 20 when it is at its inner. (lower) and outer (upper) dead center positions, lengthens in comparison with the length of the intercept when the reference axis 53 passes through the axis 21. Consequently such angular adjustment of the housing 49 represents'an especially convenient and simple mode of adjustment for varying the amplitude of reciprocation of the rack 45, and hence the angular displacement of the input element 35 of the stock feeding devices.

The housing is held in a stationary position during operation of the press and stock feeding devices by adjustment means, 56 and it is, therefore, a simple matter to provide an adjustment mechanism for varying its position angularly about the axis of shaft 37. The adjust'ment means may thus comprise a screw-threaded spindle 57 journalled at one end in a bearing 58 retaining the spindle against axial displacement while permitting it to be rotated and to rock about a horizontal axis, the bearing for this purpose having a pintle 59 rotatable in a bore in a supporting bracket or arm :60 secured to the frame of the press. The spindle 57 carries a nut 61.. which is rockably or pivotally connected by means of a pin portion 65 to a lug 62 on the upper part of the tubular portion 51 of the housing 49 so as to lie in a position offset radially from the axis of shaft 37. Rotation of the spindle 57 by hand crank 66 effects the required angular adjustment of the housing 49. The pitch of thescrew of the spindle 57 is such that the adjustment means provides a self-locking action in each adjusted position. However, if desired, clamping means could be provided separately from the threaded spindle and nut or, if desired, in association therewith, for effecting locking of the housing 49 in any adjusted position.

Typically, but not in a limiting sense. angular adjustment of the'housing 49 can provide adjustment of the feed step imparted to the stock by an amount in the order of three-sixteenths inch in a total feed step in the order of 6 inches.

The hand of the spiral gears 41a, 42a may be arranged to provide forward feeding of the stockon either the upstroke or the downstroke of the rack 45. The former is preferred since minimization of random variations due to lateral deflection of the link barv 47 and rack 45 under endwise compression are to be avoided to achieve very high accuracy of the feed step.

Referring now to FIG. 5, this illustrates diagrammatically the application of the invention to the transmission of drive to a stock feeding device situated at the exit side of the bed or table from the stock feeding device situated at the infeed side. The coupling means in accordance with the invention has the capability of providing corrective or fine adjustment to compensate for stretching of the stock, or other similar phenomenon which may from time to time occur.

An oscillatory element of one of these stock feeding devices is coupled to the corresponding oscillatory element of the other of the stock feeding devices. For convenience in the diagrammatic illustration of FIG. 5 it is assumed that such corresponding elements oscillate about horizontal axes 73a, 73b extending transversely of the feed path. Coupling is effected by provision of two rack and pinion mechanisms wherein the pinions 70a, 70b mesh with the racks 71a, 71b and the latter are guided by housings 72a, 72b. of the same general form as the housing 49 already described. The racks are coupled to each other by a further link means 79 conveniently in the form of a single link bar 74.

It will be understood that the rack and pinion and housing assembly 70a, 71a, 72a on the infeed stock feeding device will normally be separate from' that which serves to transmit drive to the input element of the associated stock feeding device from the variable throw crank 19, but there may be cases where the relative positions of the variable throw crank and housing 72a render it possible for the pinion 70a and housing 72a to be used for both purposes with both racks meshing with the pinion 70a. That is, one rack 71a, as shown, may be connected to :link bar 74, and the further rack may be connected to the variable throw crank 19 by a link bar similar to 47.

The housing 72b is arranged to be angularly adjustable about the axis 73b by any suitable mechanism, for example a screw and nut mechanism as previously described.

The angular relation between the reference axis 76 of the link bar 74, as defined by a line drawn through the axes of pins 78 and 75, and the reference axis 77b of the guideway of housing 72b controls the amplitude of reciprocation of the rack element 71b relative tothe amplitude of reciprocation of the rack element 71a.

These amplitudes will be equal when the reference axes 77a, 77b of the guideways are co-linear'with, or parallel to, each other. The amplitude of reciprocation of the rack element 7lb will be increased for angular positions of the housing 72b such as that illustrated in FIG. 5 where there is an oblique relation between the reference axes 77a and 77b of the guideways.

The arrangement illustrated in FIG. 5 may be employed even though transmission of drive to the stock feeding device at one side, for example the infeed side, of the machine is by a conventional coupling means.

What is claimed is:

1. In a device for feeding stock stepwise through a machine in synchronism with the driving member of the machine comprising a rotary input member, an eccentric on said driving member, and means for coupling said eccentric to said rotary input member including a pinion drivingly connected to said input member, a rack meshing with said pinion, and link means for pivotally connecting said rack with said eccentric, the combination of means for providing fine adjustments in the amount of stock advanced on each stroke of the feeding device including adjustable guide means defining a predetermined path of reciprocation of said rack in meshing relation with said pinion, said guide means remaining in fixed position during operation of said feeding device, and means to adjust the guide means and vary the angular relation between a first reference axis extending longitudinally of the link means and a second reference axis presented by the path of reciprocation of the rack so that a given throw of said eccentric produces different amplitudes of reciprocation of said rack and hence different amplitudes of oscillation of said rotary input member.

2. The stock feeding adjustment mechanism of claim 1 wherein said guide means is mounted for angular adjustment about the axis of oscillation of said rotary input member, and the means to adjust said guide means comprises as manipulative device for setting the guide means in any selected one of a plurality of positions about this axis.

3. The stock feeding adjustment mechanism of claim elongated tubular portion near one end thereof and a fixture mounted on the frame of the machine.

4. In a device for feeding stock stepwise through a machine having a frame and a driving member supported on said frame, the combination of an input member supported for rotation on said frame; means for coupling said rotary input member to said driving member including an oscillatory element drivingly connected to said input member, a reciprocatory element in operative engagement with said oscillatory element, and link means connected between said reciprocatory element and said driving member; and means for providing fine adjustments in the amount of stock advanced on each stroke of the feeding device including means supported on said frame and adapted to be secured in different fixed positions thereon for varying the geometry of said reciprocatory element and said link means and thereby the velocity ratio afforded between said driving element and said rotary input member, and selectively operable means for adjusting the position of said varying means while the device is in operation to alter the geometry and hence the amplitude of oscillation of said input member. 

1. In a device for feeding stock stepwise through a machine in synchronism with the driving member of the machine comprising a rotary input member, an eccentric on said driving member, and means for coupling said eccentric to said rotary input member including a pinion drivingly connected to said input member, a rack meshing with said pinion, and link means for pivotally connecting said rack with said eccentric, the combination of means for providing fine adjustments in the amount of stock advanced on each stroke of the feeding device including adjustable guide means defining a predetermined path of reciprocation of said rack in meshing relation with said pinion, said guide means remaining in fixed position during operation of said feeding device, and means to adjust the guide means and vary the angular relation between a first reference axis extending longitudinally of the link means and a second reference axis presented by the path of reciprocation of the rack so that a given throw of said eccentric produces different amplitudes of reciprocation of said rack and hence different amplitudes of oscillation of said rotary input member.
 2. The stock feeding adjustment mechanism of claim 1 wherein said guide means is mounted for angular adjustment about the axis of oscillation of said rotary input member, and the means to adjust said guide means comprises as manipulative device for setting the guide means in any selected one of a plurality of positions about this axis.
 3. The stock feeding adjustment mechanism of claim 2 wherein said guide means comprises a housing having an elongated tubular portion of which the rack element is slidably received and which extends generally tangentially of said pinion, and the means to adjust said guide means is operatively connected between said elongated tubular portion near one end thereof and a fixture mounted on the frame of the machine.
 4. In a device for feeding stock stepwise through a machine having a frame and a driving member supported on said frame, the combination of an input member supported for rotation on said frame; means for coupling said rotary input member to said driving member including an oscillatory element drivingly connected to said input member, a reciprocatory element in operative engagement with said oscillatory element, and link means connected between said reciprocatory element and said driving member; and means for providing fine adjustments in the amount of stock advanced on each stroke of the feeding device including means supported on said frame and adapted to be secured in different fixed positions thereon for varying the geometry of said reciprocatory element and said link means and thereby the velocity ratio afforded between said driving element and said rotary input member, and selectively operable means for adjusting the position of said varying means while the device is in operation to alter the geometry and hence the amplitude of oscillation of said input member. 